A modern disease with historical roots
It sometimes seems that allergy is a modern issue that only emerged at the beginning of the 20th century. At that time, Clemens von Pirquet introduced the term ‘ALLERRGIA’. However, ancient records attesting to the occurrence of anaphylactic shock appear as early as the Babylonian Talmud of the 2nd century BC. Hippocrates, who lived at the turn of the 5th and 4th centuries BC, described gastrointestinal symptoms and the onset of urticaria in a patient after milk consumption. Modern allergology probably began with John Bostock (1773-1846). The scientist described the symptoms of ‘hay fever’ at a meeting of the Royal London Medical Society in 1819 [1].
It is true, however, that allergies were relatively rare until the early 20th century. The generation of the mid-20th century was the one that began to struggle with the so-called first wave of allergies. Patients reported symptoms of inhalant allergy in the form of allergic rhinitis and bronchial asthma. At that time, thinking about food allergy, the main focus was on the problem of hypersensitivity in children. However, the turn of the 20th and 21st centuries marked a period when the picture of allergy in developed countries began to change. More and more adults started to report disordered symptoms after the consumption of various foods. In addition, it was observed that fewer children were ‘growing out’ of their allergies, and the problem in many patients could persist into adulthood. This phenomenon has been referred to as the second wave of the global allergy epidemic [2, 3].
Food allergy has now become a relatively common problem. It affects, depending on the methodology and the population studied, between 1 and 10% of the population of the United States of America [4]. In Europe, according to some studies, the problem affects about 5.9% of the population, and in Canada it is 6.7% [5, 6].
Food allergy – is it always the case?
Does every symptom that a patient associates with food consumption correspond to a food allergy? Of course not. Some symptoms are simply due to dietary errors; others are due to food intolerances of various etiologies, such as lactose intolerance, for example. The current issue of Allergy Zone focuses on the phenomenon of food allergy, with particular emphasis on the issue of IgE-dependent hypersensitivity. However, we must be aware that the nature of a patient’s abnormal symptoms is not always easy to answer. Differentiating the etiology of symptoms is of key importance in determining the patient’s treatment plan, and should therefore be the primary goal of ongoing diagnostics [7].
Food allergies: the big eight
What are the most common allergens? Extensive research has shown significant differences between the foods that sensitize children and adults. The most important allergens belong to the so-called Big Eight food allergens, which include cow’s milk, hen’s egg, fish, shellfish, tree nuts, peanuts, wheat, and soy. This term was created by the US FDA (Food and Drug Administration) and indicates the sources of allergens that must be listed on the food packaging if they are included in the product [8, 9]. In children, cow’s milk and egg proteins are the most common allergens, while in adults fish, seafood and allergens of plant origin (nuts, celery, tomatoes, and spices) are the most common [10].
Where do these problems come from?
Food allergens are proteins, usually with an average molecular weight of 15-40 kDa and water-soluble glycoproteins with a molecular weight of 10-70 kDa [10]. There are links between a protein’s resistance to temperature, acids and bases, as well as digestion in the human gastrointestinal tract, and the strength of the allergens and their ability to induce life-threatening reactions. A typical example of proteins that are very dangerous for allergic patients yet extremely resistant to heat and digestion are peanut storage proteins [11].
Thanks to the development of diagnostic methods, we know more and more about allergenic foods. However, we are still searching for answers to key, interesting and controversial questions: Why has food allergy become such a serious problem? Why is there an increasing number of patients struggling with this condition?
There are many hypotheses. Atopy is certainly a multigene inherited condition. Hygiene theories, environmental pollution, and changes in eating habits are mentioned. The excessive use of antibiotics, which negatively affects the gastrointestinal microbiome, and the overuse of proton pump inhibitors (a group of drugs used to treat diseases dependent on gastric acid secretion) are worth considering. An irregular lifestyle, stress and poor diet can also have a negative impact on the body’s immune system. Research into the aetiopathogenesis of food allergy is ongoing, with new facts coming in all the time. However, there seems to be no single, simple answer to the question of the cause of the problem. Rather, the onset of allergy is influenced by a number of factors that occur simultaneously and are necessary for the immune balance to be broken and the loss of tolerance to particular foods [12, 13].
Food allergy, or not just avoidance?
Treatment of food allergy, despite significant advances and developments in diagnostic methods, is still largely based on an elimination diet. In 2020, the FDA approved the world’s first oral immunotherapy for people following anaphylactic reactions related to peanut allergy [14]. Research into non-specific desensitizing vaccines is ongoing. The use of various forms of biological treatment in the prevention of anaphylaxis is under consideration. However, the treatments currently available are still inadequate, particularly for patients with polyvalent allergy. Patients at risk of food allergy-related anaphylaxis cannot avoid the risk 100% and are required to carry an emergency kit containing adrenaline [15].
Food allergy, a difficult disease with huge challenges
More and more mention is now being made of the psychological aspect of food allergy. About the emotional problems that this condition generates in patients at school and at work. Anxiety about eating in unknown places, fear of anaphylaxis or even death accompany some patients every day. It is worth remembering what a logistical challenge food allergy can be for entire families [16].
Research into the causes of food allergy is one of the most important studies currently being conducted in allergology. Early appropriate interventions to prevent sensitization will certainly be the most effective way to combat this epidemic of the 20th and 21st centuries.
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translation: Julia Majsiak
